Photoflash lamp

ABSTRACT

A percussive-type photoflash lamp in which the anvil of the primer is a wire on a segment of which the fulminating material is located, the wire having first and second sets of swaged protuberances in the form of lobes which aid in supporting the wire anvil coaxially within the the primer tube to provide a clearance between the coating of fulminating material and the inner wall of the tube. The second set of lobes are located immediately above and at right angles with respect to the first set of lobes.

[72] Inventor:

United States Patent Brown [54] PHOTOFLASH LAMP Stephen V. Brown, Williamsport, Pa.

731 Assignee: Sylvania Electric Products Inc.

221 Filed: Nov. 27, 1970 [2]] Appl. N0.: 93,109

[52 vs. C] Q. ..431/93 [51] Int. Cl ..F2lk 5/02 [58] Field of Search ..43 H93 [56] References Cited UNITED STATES PATENTS 3,535,063 10/1970 Anderson et al. ..43 1/93 3,535,064 10/1970 Anderson et al. ..431/93 1 Oct. 24, 1972 Primary Examiner-Edward J. Michael Attorney-Norman J. OMalley and Edward 1. Coleman [57] ABSTRACT 2 Claims, 3 Drawing Figures PATENTED-um 24 m2 STEPHEN v BROWN IVENTOR 1 PHOTOFLASII LAMP This invention relates to the manufacture of photoflash lamps and more particularly those of the percussive type.

Generally speaking a percussive-type photoflash lamp comprises an hermetically sealed, light-transmitting envelope containing a source of actinic light having a primer secured thereto. More particularly, a

percussive-type photoflash lamp may comprise a length of glass tubing constricted to a tip at one end thereof and having a primer sealed therein at the other end thereof. The length of glass tubing which defines the lamp envelope contains a combustible such as shredded zirconium foil and a combustion-supporting gas such as oxygen. The primer may comprise a metal tube and a charge of fulminating material on a wire anvil supported therein. Operation of the lamp is initiated by an impact onto the tube of the primer to cause deflagration of the fulminating material on the wire anvil up through the tube to ignite the combustible disposed in the lamp envelope.

Heretofore, in lamps of this type the anvil was a straight length of wire dropped into the tube and crimped near the bottom of the tube to support it therein. This arrangement never proved entirely satisfactory for several reasons. Frequently the fulminating material ignited during insertion and crimping of the wire anvil. Movement of the wire anvil and subsequent indefinite positioning of the fulminating material resulted in poor lamp reliability. Such lamps were extremely sensitive to jarring and handling, and accidental ignitions were frequent. The fulminating material was applied to the wirein the form of a band by transfer of a droplet while rotating the wire. Poor control of fulminating material weight with this application technique gave rise to highly variable light output and timing from one lamp to another. The tight crimp needed to hold the straight length of wire often resulted in cutting or fracture of the thin tube wall, followed by gas leakage. Molten particles often burned and/or melted through the tube witha resultant expulsion thereof through the opening produced.

In an effort to improve the weight uniformity of fulminating material from lamp-to-lamp, the fulminating material was dip-applied to one end of the wire anvil. Thus, the quantity of fulminating material applied could now be controlled by varying the rate of withdrawal of the wire anvil from the dip cup. The wire anvil was frictionally held in place by undulations formed therein at the other end thereof and frictionally engaging the inner wall of the tube within which it was disposed, thereby eliminating the problem of tube rupture during crimping. The fulminating material was positioned within the primer tube by causing that end of the wire anvil on which the fulminating material is located to bottom therein. However, this arrangement also was characterized by several deficiencies. The fulminating material frequently ignited during insertion of the wire anvil and the completed lamps were intolerably sensitive to handling. For example, a relatively slight mechanical shock would often flash the lamps regardless of where on the lamp the actual impact occurred. I

' A previous anvil construction directed toward improving support of the anvil within the primer tube employed a set of diametrically disposed protuberances above the area containing the fulminating material. This mode of support, however, provided coaxial orientation only in the vertical plane in which the protuberances were formed. Accordingly, the anvil wire was able to move in directions at right angles to the plane of the single set of lobes. As a result, the coating of fulminatingmaterial could be jarred to within close proximity of the inner wall of the primer tube to occasionally cause inadvertent ignitions.

In an attempt to improve proper centering of the anvil wire within the primer tube, another anvil construction was employed whereby four swages were pinched from the surface of the anvil wire to provide two sets of diametrically disposed protuberances, all at the same elevation. Although substantially enhancing coaxial positioning of the anvil within the primer tube, this type of construction tended to weaken the anvil wire in theswaged area due to the amount of material needed to produce the protuberances. In addition, it proved difficult to maintain the' tools required to produce the four swages.

I SUMMARY OF THE INVENTION In view of the foregoing, a principal object of this invention is to provide a percussive-type photoflash lamp having a primer structure which will withstand mechanical shock during manufacture, handling and use without premature flashing.

Another object is to provide a primer construction for percussive-type photoflash lamps that permits automated assembly without igniting the fulminating material thereof.

A' furtherobject is to provide a primer construction that affords high lamp reliability.

These and other objects, advantages and features are attained, in accordance with the principlesof this invention, by providing the wire anvil with first and second sets of diametrically disposed protuberances for supporting the anvil substantially coaxial within the primer tube, with the second set of protuberances being located above the first set of protuberances and lying in a plane substantially at right angles with respect to the plane in which the first set of protuberances lie.

BRIEF DESCRIPTION OF THE DRAWINGS This invention will be more fully described hereinafter in conjunction with the accompanying drawings, in which:

FIG. 1, is an elevational view partly in section of a percussive-type photoflash lamp including a wire anvil constructed in accordance with the invention;

FIG. 2 is a fragmentary detail on an enlarged scale of the primer of the lamp of FIG. 1; and

FIG. 3 is a cross-section taken along the line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The percussive-type photoflash lamp illustrated in the accompanying drawing comprises a length of glass tubing defining an hermetically sealed lamp envelope 2 constricted at one end to define an exhaust tip 4 and shaped to define a seal 6 about primer 8 at the other end thereof. The primer 8 comprises a metal tube 10, a wire anvil 12 and a charge of fulminating material 14. A combustible such as a filamentary zirconium 16 and a combustion-supporting gas such as oxygen are disposed within the lamp envelope.

Wire anvil 12 is provided with a protuberance, or head, 20 at the end thereof which is disposed within the primer tube 10. Further, in accordance with the invention and as particularly shown in FIGS. 2 and 3, a first set of diametrically disposed protuberances 22 are provided intermediate the ends of 'anvil- 12, and a second set of diametrically disposed protuberances 24 are located above the first set of protuberances. To provide the desired coaxial centering of the anvil within tube 10, the set of protuberances 24 are located so as to lie in a plane substantially at right angles with respect to the plane in which the set of protuberances 22 lie.

The fulminating material 14 may be dip applied to the wire anvil below the protuberances 22 and subsequently removed from the head 20 so that the entire body of fulminating material is located between the head 20 and the protuberances 22. The diameter of the head 20 and the diameter of a circumscribed circle about the protuberances 22 and 24 are larger than the diameter of the coating of fulminating material 14. Contact of the fulminating material with the inner wall of primer tube 10 is thus avoided by the provided clearance 26. A crimp 28 in the metal tube on or above head 20, positively anchors wire 12, and the protuberances 22 and 24 stabilized it within the primer tube 10.

Operation of the lamp is initiated by an impact onto the tube 10 to cause deflagration of the fulminating material 14 up through the tube to ignite combustible 16 disposed within the lamp envelope. A refractory bead 30, fused to the wire anvil 12 just above the inner mouth of the primer tube 10, eliminates burnthroughs and functions as a deflector to deflect and control the ejection of hot particles of fulminating material from the primer tube.

A method of manufacture which has been found to provide a highly reliable anvil structure particularly suited to automated assembly comprises swaging the wire anvil 12 to provide a first set of lobes as the protuberances 22, with a second set of lobes being swaged immediately above and at right angles to the first set of lobes to provide the protuberances 24, as illustrated in FIGS. 1-3. This method of construction, wherein a set of lobes 24 is swaged immediately above a set of lobes 22, provides the desired stabilization of coaxial alignment of the anvil 12 within tube 10, while at the same time maintaining the structural integrity of the anvil wire and providing a type of construction which is well suited to good dimensional control, as the relatively simple swaging operations minimize tool maintenance. A percussive-type photoflash lamp of this construction is far less sensitive to inadvertent ignition and handling and is therefore more feasible to manufacture and market. At the same time, high sensitivity to deliberate indentation of the primer tube by a firing device is maintained. Clearance 26 greatly reduces accidental ignitions of the fulminating material during insertion of the wire anvil into the primer tube and crimping thereto. The positive and uniform positionin of the fulminating material made possible by the s ructure provides a much higher lamp reliability.

What I claim is:

1. A photoflash lamp comprising:

an hermetically sealed, light-transmitting envelope;

a quantity of filamentary combustible material located within said envelope;

a combustion-supporting gas in said envelope;

and a primer secured to and extending from one end of said envelope and in communication therewith, said primer including a tube sealed in said end of said envelope and having an exposed segment outside said envelope, a wire anvil located within said tube, a body of fulminating material located on said wire anvil intermediate its ends and on that segment of said wire anvil located in said exposed segment of said tube but spaced from the inside wall thereof, a first set of diametrically disposed lobes swaged from said wire anvil intermediate its ends and above said body of fulminating material, and a second set of diametrically disposed lobes swaged from said wire anvil immediately above said first set of lobes, said second set of lobes lying in a plane substantially at right angles with respect to the plane in which said first set of lobes lie, and said first and second sets of lobes supporting said wireanvil substantially coaxial with said tube.

'2. The combination of claim 1 further including at least one supporting protuberance on the end of said wire anvil located within saidexposed segment of said tube. 

1. A photoflash lamp comprising: an hermetically sealed, light-transmitting envelope; a quantity of filamentary combustible material located within said envelope; a combustion-supporting gas in said envelope; and a primer secured to and extending from one end of said envelope and in communication therewith, said primer including a tube sealed in said end of said envelope and having an exposed segment outside said envelope, a wire anvil located within said tube, a body of fulminating material located on said wire anvil intermediate its ends and on that segment of said wire anvil located in said exposed segment of said tube but spaced from the inside wall thereof, a first set of diametrically disposed lobes swaged from said wire anvil intermediate its ends and above said body of fulminating material, and a second set of diametrically disposed lobes swaged from said wire anvil immediately above said first set of lobes, said second set of lobes lying in a plane substantially at right angles with respect to the plane in which said first set of lobes lie, and said first and second sets of lobes supporting said wire anvil substantially coaxial with said tube.
 2. The combination of claim 1 further including at least one supporting protuberance on the end of said wire anvil located within said exposed segment of said tube. 